The present invention relates to a semiconductor device, and more particularly to a semiconductor device for storing information with use of a change of a state of an electric fuse employing a breakdown of an oxide film.
A conventional semiconductor device has an electric fuse to store 1-bit information. The electric fuse is an element employing a breakdown of an oxide film. When the oxide film is in a normal state, the electric fuse has an extremely high resistance between terminals thereof. On the other hand, when the oxide film is broken down, the electric fuse has a relatively low resistance between the terminals. The breakdown of the oxide film is made by applying a predetermined high voltage between the terminals of the electric fuse. The conventional semiconductor device is configured so as to provide different outputs according to the state of the electric fuse. Thus, the conventional semiconductor device can store 1-bit information according to the resistance of the electric fuse. In the conventional semiconductor device, the electric fuse as described above may also be referred to as an anti-fuse.
The conventional semiconductor device is frequently materialized as a semiconductor memory and utilized to generate a relief address when a defective cell exists. For example, such a semiconductor memory is disclosed in Japanese laid-open patent publication No. 2004-178674.
As described above, the state of the electric fuse is changed by the predetermined high voltage. However, even if the predetermined high voltage is applied to the electric fuse in the conventional semiconductor device, no breakdown connection may be produced in the electric fuse because of process variations thereof. Accordingly, malfunction of operation may be caused in the conventional semiconductor device.